As an ESL (English as a second language) individual (with my primary language being Portuguese), I'd say understanding is way more important than grammar.
I mean, philosophical and literary (especially Shakespearean) works are "the apex of correct grammar", still those texts can often reveal themselves hard to understand. The highly-elaborate grammar didn't improve its understandability. That's because English, and human languages in general, have a lot of quirks, and they can only get so far when it comes to the expression and communication of mostly-ineffable human feelings. In fact, human languages suck when timelessness and beinglessness are involved (e.g. explaining the transcendental concept of "non-existence" (such as in Ein Sof) as something other than "nonexistent"), languages expect a "when" and "objects/subjects".
Don't worry trying to be perfect. Don't even worry to impress humans or to satisfy humans's whims, for humans themselves can't even satisfy themselves, and they won't even try to be perfect towards you despite expecting your perfectness towards them. And even if they tried, it's not feasible trying to be perfect, for we, human beings and living beings, we're far from being able of perfectness. We exist in an imperfect demiurgic Ordo, one where Chao (primordial chaos) constantly frustrates any attempt of perfection coming from self-rearranging structures, not because Chao is bad, but because Ordo is born from it.